Researchers have created a viable hybrid part-human, part-pig embryo for the first time in history. According to a study published in the journal Cell Thursday, researchers were able to successfully inject human stem cells into a pig embryo and grow tissue that would form the early stages of human organs like the heart, liver and neurons. Although it’s in the very early stages, experts believe the human-pig chimera could one day be used to grow transplantable human organs in farm animals.